The objective of this proposal is to accomplish a cross-national psychosocial typology of adolescent alcohol and drug users. Within a social learning theoretical framework, a truly psychosocial description of distinct types of adolescent alcohol/drug users will be elaborated. The project involves multiple samples of adolescents in the 13-19 age range, both within the United States and in Western Europe. Sampling will be performed so as to insure a wide range of international, intranational, ethnic, religious, and socioeconomic variations among the 2,200 to 2,500 adolescents in the study. Socio-cultural and personality characteristics of each adolescent will be assessed by means of questionnaire instruments, and these data will be analyzed within a multivariate cluster analytic framework. Of particular interest will be the identification of differential roles of sociocultural, personality, and socialization factors as they interact to produce youthful problem use of alcohol and and other drugs in the countries studied.